09/01/10 - The procedures for obtaining the MassDEP Priority Resource Maps used to support a site assessment as required by MassDEP under the Massachusetts Contingency Plan have changed. Users will continue to create the 21e site map; however, some important changes have been made.

This MassGIS page provides downloadable data showing the presumed extent of Chapter 91 jurisdiction along the coast, for reference when filing Ch. 91 applications. Digital copies of georeferenced historical maps are also available for purchase from MassGIS.

These maps are intended to help prioritize land for conservation based on the assessment of ecological communities. The maps represent a percentage of the landscape with the highest wildlife-habitat value. Activities in these areas that are subject to the Wetlands Protection regulations should conduct a detailed wildlife habitat evaluation.

Title 5 regulations prohibit the placement of septic systems immediately adjacent to certain resources. These maps display general setback areas from mapped resources; the exact extent of these areas need to be determined on the ground. Zoom into your area of interest to display all the data.

The MassDEP Wetlands Change Data Layer is a change analysis of the 1:12,000 data layer using more recent 2001 and 2005 imagery from the MassGIS Orthophotoquad mapping program. Each item in the data layer has a three element unique identifying code which indicates year of detection (WC1=2001, WC2=2005), the unique number town code, and the number of the change item during that detection year. For a complete description of the methods of this data layer, see MassGIS Datalayers
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Massachusetts Mouth of Coastal River Maps: These maps identify the Mouth Of The River (MOR) for coastal rivers in order to provide a clear, consistent, and predictable means of locating all river mouths in the Commonwealth.

Coastal Wetlands Resource Maps

These maps identify the approximate location of coastal wetlands resources for coastal communities with properties that must meet Building Code requirements for construction in a flood hazard zone, high hazard zone, or coastal dune. Please note that the delineation of coastal wetland resource areas is still determined by the issuing authority (conservation commission or MassDEP) pursuant to 310 CMR 10.00, the Wetlands Protection Act regulations. Due to the large size of these files, the maps are available via CD or DVD format only. Please contact nancy.lin@state.ma.us or alice.smith@state.ma.us for copies.